Subject: [dhcwg] DHCP Renew vs Confirm

From: Timothy Winters <[email-masked]>
Date: Tue, 14 Feb 2012 08:43:50 -0500

Hello,
	While testing some CE Router implementations we have noticed a interesting behavior that is within the specifications but not clearly documented.  I wanted to get the working group thoughts on this.

	Currently when a CE Router acting as a DHCP client, assigned both IA_NA and IA_PD, is unplugged from the network.  When reattached to the link the DHCP client transmits a DHCP Renew containing both the IA_NA and the IA_PD.

	3315 Section 18.1.2 says that when link goes down a DHCP client implementation should transmit a DHCP Confirm message containing the assigned IA_NA.

	3633 Section 12.1 doesn't allow the use of the Confirm message.  It states that DHCP Renew message, containing the assigned IA_PD, should be used when the link goes down.  

	According to the specifications a DHCP client should retransmit DHCP Confirm and DHCP Renew when link goes up.   The behavior we are seeing is the DHCP client transmits a DHCP renew containing both the IA_NA and IA_PD.   

	This behavior isn't causing interoperability issues as all the servers we have tried still respond properly to the DHCP Renew messages.

	Is it ok when a DHCP client loses link for it to transmit one DHCP Renew message?

Regards,
Tim
UNH-IOL